Superconducting Quantum Interference Devices (SQUIDs) are sensitive magnetic field devices that are capable of detecting incident electromagnetic signals and producing an electrical signal in the form of a voltage response that is proportionate to the incident electromagnetic signal. SQUIDs are particularly useful for applications requiring sensing of weak electromagnetic signals. SQUIDs can be manufactured on small integrated circuits, making them very useful for applications in which sensing of an electromagnetic signal is important, but space is at a premium.
A typical SQUID includes a loop of superconducting material including one or more Josephson junctions. The voltage response of the SQUID, also referred to as the transfer function, depends on the size of the loop. SQUIDs are typically arranged in an array of identical SQUIDs having identical loop sizes.
The transfer function and the size of the loop of a typical SQUID are geared toward detecting weak incident electromagnetic signals at relatively lower power levels. In the presence of high power sources, such as a radar source, the SQUID becomes saturated, such that the SQUID is not able to output an electrical signal representative of the incident electromagnetic signal. Hence, typical SQUID arrays are limited in the sense that they are only able to accurately sense incident electromagnetic signals and output electrical signals representative of the sensed signals over a narrow and typically low power range.
There is thus a need for a SQUID device that is able to accurately sense incident electromagnetic signals and accurately produce electrical signals representative of the sensed electromagnetic signals over a wide range of power levels.